DE102011079828A1 - Hand tool with three-point bearing - Google Patents

Abstract

The invention relates to a handheld power tool (800) having a linear motor (700) having a rotor (600), an excitation piston (400) mechanically coupled to the rotor (600) and a bearing device (100) having a rotor bearing (120) for longitudinal movement Bearings of the rotor (600) and a exciter piston bearing (180) for supporting the exciter piston (400). According to the invention, the rotor bearing (120) and the exciter piston bearing (180) form a three-point bearing, which is the only bearing for the rotor (600) and the exciter piston (400).

Description

Technical area

The invention relates to a hand tool, in particular a chiseling hand tool.

State of the art

From the publication DE 10 2007 000 488 A1 is a hand tool with driven by a linear motor pneumatic percussion known. The linear motor has a stator and a rotor. The rotor is mechanically rigidly connected to the excitation piston. The rotor of the linear motor is fork-shaped and has two bars, each of which is mounted directly in two in two along a movement axis of the rotor successively arranged air gaps of the stator. The two air gaps in the core of the stator each consist of two mutually parallel partial air gaps, which are both configured flat. The exciter piston is guided along an axis in a hollow cylinder of the striking mechanism. The two rods of the rotor are in the two air gaps - ie four partial air gaps against the stator - stored directly flat. Accordingly, the prior art hand tool has a bearing device having a rotor bearing in the form of the four-dimensional part air gaps for longitudinally movable bearings of the rotor and a exciter piston bearing in the form of a hollow cylinder for supporting the excitation piston. In the prior art hand tool, the rotor and the stator must be made very precisely matched to each other, in particular the fitting of the mechanism, in particular the air gaps, is relatively expensive. In the case of fitting errors or due to an application-related incorrect change of the fit, there is an increased risk that a runner in the air gaps will be guided in an unclean or with increased resistance or even tilted.

It is desirable in principle, with tolerable manufacturing tolerances ensure a frictionless and yet safe storage of the rotor.

Presentation of the invention

At this point, the invention begins, whose task is to provide a hand tool with a simpler designed yet reliable storage facility for storing the runner. In particular, the bearing device should be improved over the prior art and be easier to manufacture in production.

• – einen Linearmotor mit einem Läufer,
• – einen mechanisch an den Läufer starr gekoppelten Erregerkolben, und
• – einer Lagereinrichtung mit einer Läuferlagerung zum längsbeweglichen Lagern des Läufers und mit einer Erregerkolbenlagerung zum längsbeweglichen Lagern des Erregerkolbens.

This object is achieved by the invention by means of a hand tool of the type mentioned. The hand tool according to the invention comprises:

• A linear motor with a rotor,
• - A mechanically rigidly coupled to the rotor excitation piston, and
• - A bearing device with a rotor bearing for longitudinally movable bearings of the rotor and with a exciter piston bearing for longitudinally movable bearings of the exciter piston.

According to the invention it is further provided that the rotor bearing has a first bearing and a second bearing, which support the rotor on opposite sides, wherein the rotor bearing allows pivoting of the rotor together with the exciter piston about the at least one axis transverse to the axis of movement, and the excitation piston bearing has a third bearing with a longitudinal guide along a movement axis for the exciter piston.

The invention is based on the consideration that in the previously known hand tool machine, the bearing of the rotor of the linear motor is already overdetermined several times, namely by the four planar partial air gaps, which requires a complicated fitting of these bearings as a result. If an elaborate fitting should be avoided, on the one hand there would be the possibility to make the manufacturing tolerances very low, but this would lead to a comparatively expensive hand tool. Another possibility would be to accept erroneous positions of the runner in the storage facility. However, this results in a friction caused by considerable heat generation, which would ultimately negatively affect the life. The invention assumes that both approaches are disadvantageous.

The invention has recognized that a rotor bearing with a first bearing and a second bearing, which support the rotor on opposite sides, as well as an exciter piston bearing is basically advantageous. A third bearing of the excitation piston bearing thereby provides a longitudinal guide along a movement axis for the exciter piston.

Such a system of a storage facility is not overdetermined, as clearly defined by three camps. According to the concept of the invention, therefore, the assembly of excitation piston and rotor is viewed as a whole and provided a bearing device which provides a statically determined, but not overdetermined storage for the assembly of exciter piston and rotor. In the context of a particularly advantageous development, the rotor bearing and the exciter piston bearing form a first, second and third camp idealized a three-point bearing.

Moreover, according to the invention, the rotor bearing allows pivoting of the rotor together with the excitation piston about the at least one axis lying transversely to the axis of movement. This also provides a degree of freedom in the movement of the runner, which may be advantageous in work operation as well as in an assembly of the rotor in the rotor bearing.

In particular, a pivoting possibility of the rotor is limited in its amplitude; so a reliable and not over-determined storage of the runner is guaranteed. Preferably, the first bearing part comprises the rotor laterally and on a top and bottom of the rotor. As a result, the runner is stored very safe. In particular, the rotor is supported with play to allow a sufficiently low-resistance longitudinal movement of the rotor in the first and second bearings.

Further advantageous developments of the invention are specified in the subclaims and specify in particular advantageous possibilities to realize the above-described concept within the scope of the problem as well as with regard to further advantages.

A particularly advantageous development of the invention is based on the assumption that a rotor of the prior art held and guided directly in the stator can still be improved with regard to its mounting. The invention is based on the consideration that it is advantageous to consider a longitudinally movable guide of the rotor on the one hand and a holder of the rotor on the motor or housing separately.

• – ein erstes Lagerteil aufweist, das den Läufer, insbesondere seitlich und auf einer Ober- und Unterseite, umgreift, und
• – ein zweites Lagerteil aufweist, in dem das erste Lagerteil entlang wenigstens einer zur Bewegungsachse quer liegenden Achse beweglich ist, vorzugsweise begrenzt beweglich gehalten ist.

Accordingly, the development provides that the first and the second camp respectively

• - Has a first bearing part, which surrounds the rotor, in particular laterally and on a top and bottom, and
• - Has a second bearing part, in which the first bearing part along at least one axis transverse to the axis of movement is movable, preferably kept limited movable.

By means of the first bearing part of the rotor is guided in an advantageous manner adapted. By means of the second bearing part, the rotor bearing first bearing part along at least one axis transverse to the axis of movement is advantageously kept limited movable.

Preferably, the bearing device is positioned in the hand tool for storing the rotor in a movement axis of a tool of the power tool.

Conceptually, the rotor bearing and the excitation piston bearing preferably form a three-point bearing. According to the concept of this development, a three-point bearing for supporting an assembly comprising a rotor and a mechanically rigidly coupled excitation piston is provided. In departure from the storage device according to the prior art, a rotor bearing and a exciter piston bearing are provided according to the concept of the invention for supporting the rotor, which preferably form a three-point bearing. Provided with particular advantage, the three-point bearing forms the only storage for the rotor and the excitation piston.

Advantageously, the rotor bearing has a comparatively small bearing surface or bearing line proportion compared to the total surface of the assembly. Advantageously, the exciter piston bearing has a comparatively very small bearing surface or bearing line component in comparison to the overall surface of the assembly. Accordingly, the rotor bearing and excitation piston bearing for the assembly can be described at least approximately as a three-point bearing.

The invention has recognized that the disadvantages mentioned arise due to an overdetermined storage for a runner and strengthen themselves by a mechanically coupled to the rotor exciter piston. This is due to the fact that the exciter piston also assumes leadership functions and can thus initiate so-called constraining forces in bearings for the linear motor. So far, such constraining forces could be avoided only by very low manufacturing tolerances, ie by a very precise fitting of the bearings, or by elastic intermediate elements, such as a so-called pendulum support. However, this leads to a relatively expensive manufacturing process for the power tool.

In a particularly advantageous manner, the bearing device of the power tool uses the excitation piston as a guide. The assembly of exciter piston and rotor is then mounted in three points, preferably two bearing points are provided for the rotor and a bearing point is realized by the excitation piston mounted in a hollow cylinder itself. Thus, the storage device is statically determined in a particularly preferred manner, but not overdetermined. Therefore arise during operation of the linear motor of the power tool no unnecessary constraining forces and / or constraints and it is also no elaborate fitting necessary. In addition, the friction forces are relatively low, so that comparatively little heat due to frictional forces develops during operation of the power tool, which has a positive effect on the efficiency and on the life of the power tool in the result.

In the context of a particularly preferred constructive development, the bearing device with the rotor bearing and the excitation piston bearing forms the three-point bearing as the only storage, in particular by two opposing bearing points for the rotor and a bearing point for the excitation piston. The excitation piston can be circumferentially flush fitted in a hollow cylinder of a pneumatic hammer mechanism and be guided in the hollow cylinder along a working axis guided by the hollow cylinder. The exciter piston drives via an air spring on a likewise arranged in the hollow cylinder percussion piston. The exciter piston and the hollow cylinder form another bearing point. The two bearing points for the runner can be, for example, flat recesses into which the runner engages.

Particularly preferably, the first and second bearings are formed separately from a stator of the linear motor. In each case the second bearing part is preferably on the linear motor, for. B. attached to the stator and / or held on the housing.

In a particularly preferred further development variant, the rotor bearing for supporting the rotor on a fixed with a spherical spherical body. The spherical body is attached in the hand tool via at least one cap. Due to the spherical shape virtually no moments are transmitted between the spherical body and the dome, but at most forces. Thus, the rotor bearing is statically determined in a particularly improved manner, but not overdetermined. The dome is mounted for mounting the spherical body within the housing of the power tool.

For example, the spherical body has a groove into which the rotor can engage. This groove is preferably formed by a flat recess in the spherical body, which is preferably approximately parallel to a cross-sectional area, preferably practically around an equatorial surface of the spherical body.

Thus, forces and moments between the rotor and the spherical body are transmitted through this groove. The spherical body transmits to the calotte, however, only forces and no moments, which has a favorable effect on the entire storage. The groove itself has a comparatively small bearing surface or bearing line proportion compared to the total area of the assembly.

When producing the spherical body, a bulge, for example in the form of a chip or a sprue pin or a discharge lug arise. In a preferred further development variant, the calotte of the rotor bearing has a recess for embracing such a bulge of the spherical body. Such a recess can be realized by a through hole or by a blind hole. Said recess has the advantage that the above-mentioned bulge on the spherical body does not have to be removed consuming, but finally, if necessary, can be left with little laborious processing in the manufacturing process on the spherical body; especially when mounting the dome in the recess is easily absorbed later.

In order to enable a twisting or tilting between the spherical body and the dome, the recess in the dome is preferably designed such that it may comprise a larger volume than that of the bulge.

According to another preferred further development variant, the rotor bearing for biasing the calotte against the spherical body has a spring arrangement, in particular a plate spring. The spring arrangement may be provided on one side. Thus, it requires only a few parts for the spring assembly, which reduces the wear of the parts and the complexity of the rotor bearing.

In the context of a refinement which is even further improved in terms of reliability, a further calotte can be provided. This allows a particularly secure attachment of the rotor bearing. There may be provided two springs which clamp both calottes against the spherical body.

In the context of another preferred constructive development of the rotor of the linear motor of the power tool is spatförmig. Ie. the rotor preferably has a rectangular cross section and a rectangular longitudinal section, as well as an overall flat structure. This spatula-shaped rotor preferably engages even in the groove of the spherical body.

The mechanical coupling between the rotor and the excitation piston is preferably rigid, for example, formed by a rigid rod. The excitation piston bearing has, in a preferred further development variant, a hollow cylinder whose cavity is designed to support the exciter piston. In this case, moments between the excitation piston and the rod are not supported, since such excitation piston bearing acts much like a ball joint.

In particular, the excitation piston is designed comparatively short in the axial direction and preferably has a barrel-shaped outer contour. A dimension of the excitation piston along a working axis of the pneumatic impact mechanism is, for example, less than 50% of the diameter of the exciter piston. In particular, a dimension of the exciter piston along a working axis is substantially shorter than the rigid connection between exciter piston and rotor.

For example, a cylinder jacket surface may be provided with a sealing ring arranged in this. In particular, the sealing ring, for example in the form of an O-ring, be formed. Appropriately, the sealing ring may protrude from the lateral surface and is in contact with the inner surface of the hollow cylinder.

In a preferred embodiment, the rotor bearing has a first spherical body, which is fastened via first, in particular two, calotte in the power tool, and a second spherical body which is attached via second, in particular two, calotte in the power tool on. These two spherical bodies are preferably arranged opposite each other.

Conveniently, the first spherical body has a first groove and the second spherical body has a second groove, wherein the rotor - preferably spatially - engages in the first groove and in the second groove. Accordingly, the first groove and the second groove preferably lie in a plane that includes a rotor movement axis.

Particularly preferably, the bearing device is positioned in the hand tool machine for a bearing of the rotor in a movement axis of a tool, which is driven by a mechanical transmission of the exciter piston. This leads to a particularly compact design of the power tool with a high efficiency.

The hand tool has, for example, an electropneumatic hammer mechanism, which is driven by the rotor. For example, the hand tool is a hammer drill or a chiseling hand tool.

embodiments

Embodiments of the invention will now be described below with reference to the drawing. This is not necessarily to scale the embodiments, but the drawing, where appropriate for explanation, executed in a schematized and / or slightly distorted form. With regard to additions to the teachings directly recognizable from the drawing reference is made to the relevant prior art. It should be noted that various modifications and changes may be made in the form and detail of an embodiment without departing from the general idea of the invention. The disclosed in the description, in the drawing and in the claims features of the invention may be essential both individually and in any combination for the development of the invention. In addition, all combinations of at least two of the features disclosed in the description, the drawings and / or the claims fall within the scope of the invention. The general idea of the invention is not limited to the exact form or detail of the preferred embodiment shown and described below or limited to an article which would be limited in comparison to the subject matter claimed in the claims. For the given design ranges, values within the stated limits should also be disclosed as limit values and be arbitrarily usable and claimable. For simplicity, the same reference numerals are used below for identical or similar parts or parts with identical or similar function.

Further advantages, features and details of the invention will become apparent from the following description of the preferred embodiments and from the drawing; this shows in a schematic representation:

1 : An embodiment of a hand tool with a rotor having a linear motor, an excitation piston and a bearing device;

2 : An embodiment of a bearing device with a rotor bearing and a exciter piston bearing;

3 an embodiment of the exciting piston bearing;

4 : an embodiment of the rotor bearing.

1 shows schematically as an example a chiseling hand tool 800 , The hand tool machine 800 has a housing 801 with a tool holder 802 into which a shaft end 803 a tool 200 , z. B. with one of the chisel 804 , can be used. A primary drive of the power tool 800 forms a linear motor 700 , which is a pneumatic impact mechanism 806 drives. A user can use the hand tool 800 by means of a handle 808 lead and by means of a system switch 809 put into operation. In operation drives the hand tool 800 the chisel 804 continuously along a movement axis 210 in the direction of impact 213 in a subsoil.

The percussion 806 has a pathogen - here in the form of an exciter piston 400 - and a racket - here in the form of a percussion piston 300 - that in a guide tube 510 a exciter piston bearing 180 of the percussion mechanism 806 along the axis of movement 210 are movably guided. The exciter piston 400 is via a mechanical coupling 500 in the form of a rod to the linear motor 700 coupled and forced to a periodic, linear motion. An air spring - formed by a pneumatic chamber 301 - between the exciter and the racket, movement of the racket is linked to the movement of the pathogen. In the present case, the percussion piston 300 directly on a back end of the tool 200 strike or indirectly through a substantially dormant intermediate racket part of his impulse, here on the chisel 804 , transfer.

2 shows a schematic representation of an embodiment of a storage facility 100 with a runner storage 120 ,

4 shows a first and second camp 10 . 20 the runner storage 120 in detail in an exploded view and to this reference is made.

Out 3 is in a detailed view of the storage facility 100 associated exciter piston bearing 180 seen.

For storing a runner 600 a linear motor 700 is the storage facility 100 according to the concept of the invention in a hand tool 800 - for example, in the manner of a 1 schematically illustrated embodiment - integrated. The runner 600 , the guide tube 510 and the exciter piston 400 are in a movement axis 210 stored, along which a tool 200 the hand tool machine 800 can move.

The storage facility 100 according to 2 forms with its two-part - a first and second camp 10 . 20 having - runner storage 120 and theirs - a third camp 30 having - exciter piston bearing 180 a certain, but not overdetermined three-point storage. The storage facility 100 Thus, the module outsourced via a mechanical coupling 500 connected exciter piston 400 and runners 600 ; In other words, the assembly is of exciter piston 400 and runners 600 stored in its entirety; not the exciter piston 400 and runners 600 stored separately from each other. The following are the three idealized - through the first second and third camp 10 . 20 . 30 formed - bearing points of the three-point bearing explained. In particular, the details of the 3 and 4 Referenced.

The exciter piston 400 has a barrel-shaped outer contour and is in a exciter piston bearing 180 with a guide tube 510 in the form of a hollow cylinder 182 stored. The exciter piston 400 can along the cavity 184 of the hollow cylinder 182 glide along. For this purpose, the exciter piston has a cylinder jacket surface 410 with a arranged in this sealing ring 420 For example, an O-ring on. The exciter piston 400 has a cylinder jacket surface 410 on, which - mediates on the sealing ring 420 - Airtight on an inside of the hollow cylinder 182 is feasible.

The exciter piston 400 is over a rod of mechanical coupling 500 in the guide tube 510 mechanically to the spatulate runner 600 coupled. The spatulate runner 600 is guided in two first bearing parts, which are present as two spherical bodies 122 . 124 are formed. The runner 600 lies in two grooves 142 . 144 the two spherical bodies 122 . 124 , The spherical bodies 122 . 124 form insofar in the area of their grooves 142 . 144 two of the three bearing points of the storage facility 100 ,

Conveniently, each groove 142 . 144 in the spherical body 122 . 124 dimensioned such that a surface pressure between the rotor 600 and the spherical body 122 . 124 does not exceed a predetermined maximum. As a result, the storage facility 100 the hand tool machine 800 be dimensioned in terms of a given operating time. Thus, depending on forces between runners 600 and rotor bearing the sizes of the surfaces in the groove 142 . 144 very different. Through the surfaces of the groove 142 . 144 in the spherical body 122 . 124 in the present case, the minimum diameter of the spherical body 122 . 124 influenced. The dimensions of a dome explained below 132 . 134 are tuned to it.

In the production of the spherical body 122 . 124 can bulge 126 arise, for example in the form of chip points in a machining production or in the form of a sprue pin or a discharge projection in an injection molding production process. That's why the first two calottes 132 a recess 136 on top of those bulges 126 include.

Each of the two first bearing parts is thus limited movably held in two second bearing parts; and in the present limited movable along at least a first transverse to the axis of movement 210 lying axis 211 and also along at least one second - other - transverse to the axis of motion 210 lying axis 212 , The movement axis 210 and the transverse axes 211 . 212 in the present case form a Cartesian coordinate system. The two second bearing parts are present in each case via two calottes 132 . 134 in the stator 650 of the linear motor 700 attached.

According to the schematic in 4 illustrated construction of a rotor bearing 120 is the runner 600 in a central position of the spherical body 122 with the first groove 142 and a center position of the spherical body 124 with the second groove 144 guided longitudinally movable. In this respect, the idealized points of the three-point bearing correspond to the bearing points 1 . 2 . 3 , The third camp point 3 It marks approximately one centroid of the exciter piston 400 - Here is a crossing point of the movement axis 210 with a diameter D of the exciter piston 400 transverse to the axis of movement 210 ,

Due to the spherical shape are between the first spherical body 122 and the first dome 132 no moments, but at most transmit powers. To a bias of the first calottes 132 against the first spherical body 122 to obtain are at the in 4 illustrated embodiment disc springs 150 intended. The disc springs 150 in the present case, on one side only - in one embodiment, not shown here, on two sides - the first calottes 132 against the first spherical body 122 , The first and second camp 10 . 20 are similar here, mirrored here, formed, so that 4 applies to both.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 102007000488 A1 [0002]

Claims (15)

Hand tool machine ( 800 ) comprising: - a linear motor ( 700 ) with a runner ( 600 ), - one mechanically to the runner ( 600 ) rigidly coupled exciter pistons ( 400 ), and - a storage facility ( 100 ) with a rotor bearing ( 120 ) for longitudinally movable bearing of the runner ( 600 ) and with a exciter piston bearing ( 180 ) for longitudinally movable bearings of the exciter piston ( 400 ), characterized in that - the rotor bearing ( 120 ) a first warehouse ( 10 ) and a second warehouse ( 20 ), which the runner ( 600 ) on opposite sides, the rotor bearing ( 120 ) a limited pivoting of the runner ( 600 ) together with the excitation piston ( 400 ) about the at least one axis of movement ( 210 ) transverse axis ( 2111 . 212 ), and - the excitation piston bearing ( 180 ) a third camp ( 30 ) with a longitudinal guide along a movement axis ( 210 ) for the excitation piston ( 400 ) having. Hand tool machine ( 800 ) according to claim 1, characterized in that the first and the second bearing ( 10 . 20 ) each having a first bearing part which the runner ( 600 ) laterally and on a top and bottom, and a second bearing part, in which the first bearing part along at least one of the movement axis ( 210 ) transverse axis ( 211 . 212 ) is kept limited mobility. Hand tool machine ( 800 ) according to claim 1 or 2, characterized in that the first and second bearings ( 10 . 20 ) separately from a stator ( 650 ) of the linear motor ( 700 ) is formed. Hand tool machine ( 800 ) according to one of claims 1 to 3, characterized in that the rotor bearing ( 120 ) and the excitation piston bearing ( 180 ) with the first, second and third bearings ( 10 . 20 . 30 ) form a three-point bearing. Hand tool machine ( 800 ) according to one of claims 1 to 4, characterized in that the first, second and third bearings ( 10 . 20 . 30 ) the rotor bearing ( 120 ) and the exciter piston bearing ( 180 ) the only storage for the runner ( 600 ) and the excitation piston ( 400 ) form. Hand tool machine ( 800 ) according to one of claims 1 to 5, characterized in that two opposing bearing points of a three-point bearing by means of the first and second bearings ( 10 . 20 ) for the runner ( 600 ) and a third bearing point of the three-point bearing by means of the third bearing ( 30 ) for the exciter piston ( 400 ) is formed. Hand tool machine ( 800 ) according to one of claims 1 to 6, characterized in that the first and second bearings ( 10 . 20 ) the rotor bearing ( 120 ) for storing the runner ( 600 ) in each case in the form of a dome ( 132 . 134 ) formed second bearing part, in which a first bearing part in the form of a spherical body ( 122 . 124 ) is limited mobility. Hand tool machine ( 800 ) according to one of claims 1 to 7, characterized in that a spherical body ( 122 . 124 ) of the first and / or second warehouse ( 10 . 20 ) a groove ( 142 . 144 ) into which the runner ( 600 ) intervenes. Hand tool machine ( 800 ) according to one of claims 1 to 8, characterized in that a dome ( 132 . 134 ) of the first and / or second warehouse ( 10 . 20 ) a recess ( 136 ) for embracing a bulge ( 126 ) of a spherical body ( 122 . 124 ) of the first and / or second warehouse ( 10 . 20 ) having. Hand tool machine ( 800 ) according to claim 9, characterized in that the recess ( 136 ) is designed to include a larger volume than that of the bulge ( 126 ). Hand tool machine ( 800 ) according to one of claims 1 to 10, characterized in that the rotor bearing ( 120 ) for preloading a dome ( 132 . 134 ) against a spherical body ( 122 . 124 ) a spring arrangement ( 150 ), in particular a plate spring. Hand tool machine ( 800 ) according to one of the preceding claims, characterized in that the first bearing ( 10 ) the rotor bearing ( 120 ) a first spherical body ( 122 ), which has a first upper-side and a first lower-side dome ( 132 ), limited mobility in the power tool ( 800 ), and the second bearing ( 10 ) the rotor bearing ( 120 ) a second spherical body ( 124 ), which has a second upper-side and a second lower-side dome ( 134 ) limited movable in the power tool ( 800 ) is attached. Hand tool machine ( 800 ) according to claim 12, characterized in that the first spherical body ( 122 ) a first groove ( 142 ) and the second spherical body ( 124 ) a second groove ( 144 ), wherein the runner ( 600 ) into the first groove ( 142 ) and into the second groove ( 144 ) intervenes. Hand tool machine ( 800 ) according to one of the preceding claims, characterized in that the third bearing ( 30 ) the excitation piston bearing ( 180 ) one along the axis of motion ( 210 ) aligned hollow cylinder ( 182 ), whose Cavity ( 184 ) is configured, the excitation piston ( 400 ) longitudinally movable and the exciter piston ( 400 ) a cylinder jacket surface ( 410 ), wherein the cylinder jacket surface ( 410 ) airtight on an inner side of the hollow cylinder ( 182 ) is feasible. Hand tool machine ( 800 ) according to claim 14, characterized in that in the cylinder jacket surface ( 410 ) a sealing ring ( 420 ) is arranged.

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